Protected fabric



Patented Sept. 19, 1922.

J GEORGE J. NIKOLAS, OF CHICAGO, ILLINOIS.

rRoTno'rEn mimic.

1T0 Drawing.

To all whom it may concern:

Be it known that I, GEORGE J. NIKOLAS, a citizen of the United States, residing at Chicago, in the county of Cook and State of proofing andfire-proofing protective coating of varnish material, advantageously pyroxylin, carrying uniformly incorporated therein impalpably fine particles of 5 fireproofing salts, i. e, such salts as carry combined water or ammonia, or both, which canv be evolved on heating; all as more fully hereinafter set forth and as claimed.

-Aeroplane wings are made with the aid of linen or cotton canvas stretched over the framework. It is necessary that the textile fabric be water-proofand that the Waterproofing be of such a character as to cause atautening action. In practice water-proofing is usuallyobtained withthe aid of pyroxylin varnishes or cellulose acetate varnishes, the treated fabric being afterwards covered with an outer layer of a good spar varnish. Neither of these water-proofing varnishes is perfectly satisfactory in use. Pyroxylin is a variety of gun cotton and of course is readily inflammable, but it furnishes varnishes which are cheaper and easier to make than those made with cellulose'acetate, and it is also a better coating material. Varnish films made with cellulose acetate varnishes are muoh less readily inflamed although they are not fire-proof. It is inpractice highly desirable to be" able to fire-proof aeroplane wings as well as waterproof them, the fire-proofing being at least sufficient in degree to prevent the spreading of combustion should the textile material start to burn at one point. The usual test for fire-proofing is to put a few drops of gasoline on a Wing and set fire to it. With a satisfactory dope the ,wing should not take fire or char. Resistance to this test can be given a pyrox ylin varnish by the expedient of incorporating hygroscopic salts such as chlorid of zinc, magnesium chlorid, calcium chlorid, etc.; these salts acting by virtue of their power of attractin moisture from the atmosphere. Virtuaily they fire-proof by keeping the fabric damp. But such compositions are not water-proof and Application filed November 21, 1918. Serial No. 263,614.

water-proofing in an aeroplane wing is even more desirable than fire-proofing. As a rule, these hygroscopic salts are simply dissolved in the solvent used for the pyroxylin.

I have found that a better type of simultaneous Water-proofing and fire-proofing can be obtained, giving textile surfaces carrying a pyroxylin varnish film Which will withstand-the a'bove test by the simple expedient of incorporating into or suspending in the varnish an impalpably' fine fire-proofing salt of the character of, alum, sulfate of soda (sodium sulfate), sulfate of alumina, borax, sulfate of ammonia, etc. All these salts, and many others like them, are permanent in air, neither taking up moisture or giving it off .at the ordinary temperature, while on heating they evolve vapors of water or ammonia, or both, with absorption of heat. By incorporating a suitable proportion of these salts into the varnish and then varnishing the fabric, on drying, the surface is left covered with a coating of pyroxylin mixed with fine grains of the salts. The pyroxylin not only water-proofs the canvas but also waterproofs the individual particles ofthese salts,

shielding them against rain, etc. On a-pplichange its character on drying. For a satisfactory coating under the present invention this is necessary.

Ordinary'ammonia alum, (A1 (S0 (NIL) SO 24H O) contains about 47 ,per cent. of water and about 4 per cent of ammonia, giving off both readily'when it is heated." Ordinary crystallized aluminum sulfate (Al (S0 18 H O) contains about the same per cent ofwater. Either is useful for the-present purposes.' Ordinary sodium sulfate (Na SO 1O H O) contains somewhat more water about 55 per cent; and it may be used. Borax also contains more than one half its weight in water and is a suitable material for the present purposes. In using any of these materials they The vapors stifle the] may be ground to an impalpably fine powder and directly mixed with the varnish by any suitable mixing device. Or they may be added to the varnish and the mixture ground in an ordinary paint mill until a uniform suspension is obtained. With a pyroxylin Varnish containing about six or seven ounces of pyroxylin to the gallon, a good proportion of fire-proofing salts is about a half pound to the gallon. With such proportions a varnish is obtained which on drying down contains finely subdivided fire-proofing salts in amount-somewhat larger than that of the pyr'oxylin present. A surface varnished with such a film may be considered as being covered with a thin film of fire-proofing salts, each granule or particle in the film being bound to and separated from the next adjacent particle by a layer of pyroxylin. The presence of this amount of fire-proofing salt in the varnish in no Way interferes with its properties of Water-proofing the canvas and Glaubers salts as a fire-proofingsalt, the proportion being about as above indicated.

While I find that for aeroplane work compositions containing pyroxylin dissolved in volatile solvents are the best adapted for the present purposes, many other varnishes may be employed. Cellulose acetate dissolved in chloroform, acetylene tetrachlorid, acetone,

'etc., may be used. A cellulose acetate varnish containing these fire-proofing salts is superior to the cellulose acetate varnish alone.

The present composition may be used for simultaneous water-proofing and fireproofing of many other things than aeroplane wings and for {treating other textiles than linen or cotton canvas, but I regard the main utility of the present invention to be with respect toaerop'lane Wings.

What I claim is: i i

1. As a new article of manufacture, alayer of fabric carrying a protective coating of varnish; material containing intimately and uniformly incorporated impalpably fine particles of fireproofing salts such salts being insoluble in solvents wherein such varnish material is soluble.

2. As a newarticle of manufacture, a layer of fabric carrying a protective coating of pyroxylin varnish material containing inti "mately and uniformly incorporated impalpably fine particles of fireproofing salts; such salts being insoluble in solvents wherein such pyroXylin varnish material is soluble.

In testimony whereof, I aifix my signature hereto.

GEORGE J. NicKoLas 

